vmod-xcounter

Custom Counter

Author:	Shohei Tanaka(@xcir)
Date:	2018-11-30
Version:	61.2
Support Varnish Version:	6.0.x 6.1.x
Check Varnish Version:	6.0.x 6.1.x
Manual section:	3

SYNOPSIS

import xcounter;

Versioning

[varnish-version].[library-version]

61.1 is v1 for Varnish6.1.x

DESCRIPTION

vmod_xcounter enables custom counter in Varnish.

varnishstat -f XCNT.*

For example, count to the number of requests per domain.

vcl sample:

import xcounter;

sub vcl_init {
  new example_net = xcounter.vsc();
}

sub vcl_recv {
  if(req.http.host ~ "^example\.net$"){
    example_net.incr(1);
  }
}

varnishstat output

$ sudo varnishstat -1 -f "XCNT.*"
XCNT.reload_20181118_042545_24957.example_net.val            1          .   xcounter

ATTENTION

The counter is linked to the VCL.

Add new entry per new(reload) VCL.

INT elapsed()

Description

Get elapsed time.

Example

if(xcounter.elapsed() > 1s){...}

vsc(...)

new xvsc = vsc(
   ENUM {bitmap, bytes, duration, integer} format=integer,
   ENUM {bitmap, counter, gauge} type=counter,
   ENUM {info, debug, diag} level=info,
   STRING oneliner="xcounter",
   BOOL hidecold=1,
   BOOL hidevclname=0,
   STRING groupname=""
)

Description

Create a counter.

Counter name format

XCNT.boot.group.object.val
("XCNT.%s.%s%s.val", vclname, groupname, objectname)

format Counter format.

type Counter type.

level Counter level.

oneliner Counter description.

hidecold Hide counter, if state of vcl becomes cold.

hidevclname Do not include vclname(boot,reload... etc) in counter name, if set to true.

groupname Add group name.

Example

new xcnt = xcounter.vsc();

VOID xvsc.incr(INT d, BOOL threadsafe=1)

Description

Increment vlaue.

Negative values are ignored

Example

xcnt.incr(1);

VOID xvsc.decr(INT d, BOOL threadsafe=1)

Description

Decrement value.

Negative values are ignored.

Example

xcnt.decr(1);

VOID xvsc.set(INT)

Description

Set value.

Example

xcnt.set(1024);

INT xvsc.get()

Description

Get current value.

Example

if(xcnt.get() > 1024){...}

INSTALLATION

The source tree is based on autotools to configure the building, and does also have the necessary bits in place to do functional unit tests using the varnishtest tool.

Building requires the Varnish header files and uses pkg-config to find the necessary paths.

Usage:

./autogen.sh
./configure

If you have installed Varnish to a non-standard directory, call autogen.sh and configure with PKG_CONFIG_PATH pointing to the appropriate path. For instance, when varnishd configure was called with --prefix=$PREFIX, use

export PKG_CONFIG_PATH=${PREFIX}/lib/pkgconfig
export ACLOCAL_PATH=${PREFIX}/share/aclocal

The module will inherit its prefix from Varnish, unless you specify a different --prefix when running the configure script for this module.

Make targets:

• make - builds the vmod.
• make install - installs your vmod.
• make check - runs the unit tests in src/tests/*.vtc.
• make distcheck - run check and prepare a tarball of the vmod.

If you build a dist tarball, you don't need any of the autotools or pkg-config. You can build the module simply by running:

./configure
make

Installation directories

By default, the vmod configure script installs the built vmod in the directory relevant to the prefix. The vmod installation directory can be overridden by passing the vmoddir variable to make install.

COMMON PROBLEMS

• configure: error: Need varnish.m4 -- see README.rst

  Check whether PKG_CONFIG_PATH and ACLOCAL_PATH were set correctly before calling autogen.sh and configure

• Incompatibilities with different Varnish Cache versions

  Make sure you build this vmod against its correspondent Varnish Cache version. For instance, to build against Varnish Cache 4.1, this vmod must be built from branch 4.1.

• Require GCC

  This vmod using GCC Atomic builtins.